Hello hope what temp do you germ your seeds at ???
I don't even measure m8 tbh.. I usually keep them a bit higher above the heat mat but I think these rockwool cubes need a bit more heat than the root riot cubes I've used before. I did my Predator and hellraiser paper tower method and transplanted into the rockwool croutons to be safe. I could be boiling these 2 in the sambo bag lol we'll see in a day or 2.